Field of the Invention: This invention relates to a cutter-loader apparatus in combination with a face conveyor commonly referred to as long wall mining apparatus. More particularly, this invention relates to such cutter-loader apparatus having an overhung shearer drum which rotates about an axis parallel to the mine floor, wherein the shearer drum is mounted on a support arm and is provided with helical whorls over the drum's cylindrical surface for laterally removing loosened spoil from the mining area to a subjacent face conveyor.
Description of the Prior Art: Drum cutter-loaders are known. German patent specification No. 21 13 399. Such devices are employed principally for working thin mining seams. The body of such apparatus is positioned close to a face conveyor and rests directly on the floor of the mine, at least in the deepest part of the mining cut. The overhung shearer drums release the mineral and remove the spoil by means of helical whorls over the cylindrical surface of the rotating shearer drum. Customarily two shearer drums are employed, each supported by a support arm which is substantially parallel to the mine floor and which is positioned adjacent to the face conveyor on the face side of the shearer drum and above the machine track. Such support arms accommodate the transmission elements which transmit the motor drive to the shearer drums and accordingly have appropriate vertical dimensions which interfere with the removal of spoil by the shearer drum, particularly when the spoil is in the form of large lumps. Such overhung shearer drums have relatively large dimensions and hence must cut the entire machine body free, requiring relatively high driving power. The shearer drum mountings are supported at one end and accordingly are sufficiently strong to accommodate appreciable cutting and shearing stresses which occur during the mining operations.
If the support arm for such apparatus were disposed in the deepest part of the mining cut, that is, on the face side of the machine body wall, spoil removal might be improved but the support arm would have to be cut free over its entire width, for example, by means of a rotating cutter chain in advance of the support arm. Such a cutter chain would require tensioning devices to maintain proper chain tension. Such devices would preclude providing a transmission inside the support arm to transmit to the shearer drum the appreciable drive power from the drive motor which is located inside the machine body. In such a machine, the rotary motion of the drive motor could be transmitted to the shearer drum by means of the cutter chain rotating support arm. Since a single cutter chain is not sufficient to transmit the required drive power for the shearer drum, appreciable power losses would be tolerated; such a drum cutter-loader could not be employed in a cost-effective manner.
In German patent specification No. 11 96 146, long wall mining machines with overhung shearer drums are disclosed. The shearer drums are supported by two lateral arms at different heights. The support arm on the face side which is situated within the seam is equipped with a cutter chain. The support arm outside the seam is provided as low as possible in order to avoid obstructing the removal of spoil material. The outside support arm transmits the power between the mining machine drive motor and the shearer drum. To accomplish this, a variable length drive shaft extends over the length of the support arm for transmitting the drive motion from the motor within the machine body to the shearer drum. The same drive shaft also, through the drum, engages the rotating cutter chain which cuts free the face side support arm.